On Saturday, November 1, 2014 5:01:04 PM UTC-7, Francesco Bonazzi wrote: > > Apart from the bug fixes, it's quite hard to go on rigorously. > > You wrote you have some hackish stuff about derivatives, on github you can > create a gist, which is usually a piece of code unrelated to a project, > which people can see and comment. >
I have made a gist with some code I wrote to do derivatives. https://gist.github.com/seniosh/ef0e1550110eec0c6b41#file-grtensor-py where can that then be discussed? I already realize several problems (partial differentiation gets treated as a Tensor, which is a problem if you want to switch coordinates), but it's a starting point for discussion at least. > If you realized, the tensor module only allows expanded polynomial > expressions, that is difficultto change because the algorithm was written > for that, and supporting something different would require a llot of > rewrite. > > I have a pending PR on the tensor module, which is a major rewrite of the > code, but I'm not very satisfied of it. > Should I move discussion to that PR? Or should I make a new one? > An alternative is to expose special objects such as partial derivatives to > the index structure of a tensor. > > If you like to do something, try to see how to create a covariant > derivative object that exposes the index structure. > > Say, CovarDerivative(i, A(j, k)) should be treated as a tensor of indices > i j k. You will realize that the way the tensor module was written makes > this task quite hard. > When I implemented it, my CovarDerivative function operated on data, and then returned a new TensMul object, so CovarDerivative(i, A(j, k)) returns dA(i, j, k). -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/ec52a9f4-e004-4a3f-901a-c7bab4a35515%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
